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Jon Somerset

Summer - From June 1st Or 21st?

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I was wondering what others feel about the date of June the 1st as the 'beginning' of summer? I for one have always experienced the period June 21st to September 20th as the 'real' summer. I'm sure that this was officially the case many years ago when I was growing up. Only recently have I noticed the met office and other official forecasters using June, July and August as summer. When did this start happening?

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Most years there isn't much summer to be had after June 21st haha.

For me, summer normally starts around May 21st as that's a pretty regular approximate date for warm settled spells to begin. The final third of May and June usually give us our best weather before Atlantic weather returns in July and August. This is when I often record my highest maxima unless a miracle happens later on in the season. Conversely, nights are still often quite cool and don't warm up until we're affected by Atlantic air with more cloud.

This year, it may be that summer doesn't get going until around the June 21st.

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1st of june I always class it, but I usually say 15th May to 15th Aug for summer, highest, strongest sun, lightest nights

Miguel, summer arrived on 21st May this year

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1st of June..

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1st of june I always class it, but I usually say 15th May to 15th Aug for summer, highest, strongest sun, lightest nights

Miguel, summer arrived on 21st May this year

True, but is now long gone again. The 'sunny' weather only lasted 5 days despite it being warm and cloudy from the 28th onwards and since the turn of the month it's been autumn. Most other years have begun around the same time and have set the trend for recurring dry/warm spells. That spell was more of a blip between an underlying spell of cool/cold and wet weather I think ... for the southwest anyway.

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June 1st for me, because of the daylight and it feels more like summer than Spring and early June is far, far more like summer than early September.

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I think that, in many old Northern European cultures, summer did begin on June 21. But, I believe that, in order to avoid confusion (an 'incomplete' success?) the meteorological start of summer, June 1, is now (almost) universally accepted?

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In Canada meteorically speaking each season begins when the sun reaches solstice or equinox..they time it to the hour for example they make a big song and dance about the changing of the seasons and will quote that summer time will be at what ever time the sun reaches its furthest point north which could be at 10.57pm or 2.03am that's when summer starts...for me here summer runs from mid July to mid August..rest of the year its winter.

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21st of June simple, it always has been and always will be

Why the 21st? Summer solstice is the 20th this year.

Contrary to popular belief, the solstices and equinoxes are not fixed dates.

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Weather site so it's June the 1st.

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21st of June simple, it always has been and always will be

No room for the Met Office that class it as the 1st June then? It's easier for them to use the 1st of June for statistical purposes due to being an easily defined time scale, and as the dates of the equinoxes change.

I've always thought of it as being the 1st June, at least for meteorological recording purposes (and this forum is a weather one). It doesn't feel right to me to have the sun going south for the entirety of summer.

Not that people can't view it as whenever they want of couse, or that what the calendar effects the actual weather outside!

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Thinking more about it I tend to prefer the summer solstice as the start of summer. Warmth builds up in the northern hemisphere so despite the nights shortening there is a lag in the mean temperature. I'm sure that my memory has many more good Septembers than Junes.

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Thinking more about it I tend to prefer the summer solstice as the start of summer. Warmth builds up in the northern hemisphere so despite the nights shortening there is a lag in the mean temperature. I'm sure that my memory has many more good Septembers than Junes.

Yes the lag in temperatures is the key factor which sways some people to believe summer starts on the 21st June rather 1st June. SSTs are much cooler in the first half of June than they are in the first half of September and the arctic is much cooler. We are much more likely to see cool northerly airstreams in the first half of June than the first half of September. However, the sun is far stronger in the first half of June than the first half of September and the extra daylength certainly for me gives credence to my belief that summer starts on the 1st June. For the NW less settled conditions are much more likely around the 21st June than they are on the 1st June.

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If you check my thread in the Historic Weather forum on daily CET values, the warmest 92 days of the year (an equal number to June-July-August) runs 13 June to 12 September. This is very close to the same period that averages above 14.0 C long-term and above 14.5 C in the warmer recent era. So from that, the older "astronomical" season is actually a closer fit than the climatological concept of three calendar months.

In the more continental climate of Toronto, Canada, I found that the warmest 92 days of the year ran from 11 June to 10 September, not vastly different.

Now, this matter of the changes year to year of the equinox and solstice dates ... that is due to our calendar being a whole number of days while the earth year is 365.2422 days. The vernal equinox is defined as the point where the earth's equatorial plane begins to point "south" relative to the Sun. The whole point of a calendar is to have a frame of reference that can make this and other similar climate-determining positions of our orbit predictable in general terms. Lunar calendars are adjusted either by observation or by mathematical formulae that seem to work, and require an added month every three years or so, to account for the 12.3 lunar months per solar year. The Romans thought they had it worked out correctly for a solar calendar that was not lunar based, with their twelve months and a leap year every fourth year. But that would only be perfect if the earth's year was 365.25 days long, not 365.2422. If the year was 365.24 years long, we could solve the problem by dropping one leap year a century. But the year is too long for that, so we drop all the leap years ending in '00 except those divisible by 400. This was the change introduced in the Gregorian calendar but by that time, 11 days had to be taken out of the inflated Julian calendar which by the 16th century had drifted backward relative to the seasons due to the extra leap years. Although Europe changed in 1582, Britain and America changed in 1752.

An example of how the calendar was out of sync with the agricultural year can be seen from the Daniel Defoe storm in 1703. The calendar then read 26-27 November but the Sun was where we now expect to find it around 8-9 December. In other words, the weather and length of day we might expect in mid-December was then experienced in late November. This meant that seasons were setting in earlier by calendar date each century after the Roman era, although inter-annual variability probably masked this trend for a long time. Also century to century changes in climate would tend to obscure a subtle trend like this, but astronomers began to notice the problems more acutely in the medieval period. This led to the Gregorian calendar which changed the schedule of leap years to prevent a future problem of the same kind, and which required that 11 days be dropped from the calendar in the year of the shift (it had been 10 days for the earlier Europeans). That instantly placed the seasons back where they should have been in the autumn of 1752. For those wondering, the CET data are adjusted so that what we see are from our time perspective and not the perspective of the people who recorded the data. An example, the cold January of 1740 was experienced then as 21 December to 20 January.

Although the Gregorian calendar forces the equinox-solstice timetable into a narrow 2-day range, it continues to oscillate due to the length of the earth year being that fraction of a day longer than most calendar years. What happens in practice is that each year, the four dates drift later by 6 hours until the leap year corrects them. Since leap year day is before any of the dates in question, all four of them move back one day and start the same process over again. The missing leap years in 1800 and 1900 allowed these dates to drift forward further than they will this century. As a result, the vernal equinox in 1903 was on 21 March at 1915 GMT, the latest it has been since the early 19th century. By 2096, the vernal equinox will achieve its earliest timing for hundreds of years, 19 March 1403 GMT. The missing leap year in 2100 will allow that too-early situation to wash out by giving eight instead of four periods of six-hour changes forward, so by 2103 the vernal equinox will be back to 21 March at 0627 GMT.

A general rule then, is that these astronomical dates move earlier towards the end of centuries, and start later each century except those such as the 21st century that don't start with a missing leap year. Comparing 2203 and 2303, the vernal equinoxes are later by about six hours on 21 March, so the entire century timetable runs about 6 hours later. Another general rule is that between leap years, dates are about six hours earlier each year, so leap years have the latest dates.

This is as close as we can come to standardizing the earth year, without perhaps dropping a leap year every 132 years instead of three in 400. The difference between 365.2422 and the Gregorian-implied 365.2425 means that there will be three too many leap years every ten thousand years, or one too many every 3 millennia. Our distant descendants may find a need to drop a leap year around 5000 AD. (I won't get arrested for saying AD on a British forum, will I? Not that I care, life in a British jail might help me lose a bit of weight)

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SST's are also colder in February than in December.. so what?

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I was wondering what others feel about the date of June the 1st as the 'beginning' of summer?

Does that include the weather.

I have always wondered why there are two starts to summer or to a season, my summer has begun on the 1st June but a friend up the road it's 21st June, he could be right on the weather side of that..

So il read the posts and maybe il find an answer to this.

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May 21st Onwards.

Ok so there is now three starts to summer.. anymore?

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june july and august i would class as summer i always have done.

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In terms of the weather we get I think the meteorological definition (1st June) works better than the astronomical definition (21st June).

If you look closely, the meteorological definition cuts out the period 1st-20th September and adds the period 1st-20th June. Despite the temperature lag, the 1st-20th September is only about as warm as the 1st-20th June on average, and the comparable warmth involves cooler days and warmer nights. Cloud cover is generally higher, and daylight hours are shorter (hence the reduced diurnal range). Rainfall is similar in the east and generally somewhat higher in the west.

The difference is felt most strongly in northern and western Britain where May and June are on average the sunniest months of the year as the jet stream and the Azores High both tend to strengthen during late June and into July bringing a steeper westerly gradient over the British Isles. In most western areas the increased cloudiness from the westerlies also tends to be accompanied by increased rainfall. Depressions tend to be relatively modest affairs during late spring and summer but by the time we get into September, large depressions with strong to gale force winds are not unusual.

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I've always said June 1st for start of Summer.

Spring: March, April and May

Summer: June, July and August

Autumn: September, October and November

Winter: December, January and February.

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